Melt butter over moderate heat, add rice and cover grains. Add fish stock, bring to boil, reduce to simmer, cover and cook for 15 mins until liquid absorbed. Set aside.
Wrap salmon fillets in foil and bake in 160°C oven for 10 mins (par-cooked).
Melt butter, sauté fennel, add mushrooms, dill and lemon juice. Add to rice, salmon and eggs. Season and mix to break up salmon. Cool.
Layer 5 sheets of filo pastry, brushing with melted butter as you go. Spoon rice mixture into middle to make a sausage shape. Fold in short edges first, then long ones. Brush with more butter and sprinkle with fennel and chia seeds.
Transfer to baking tray and cook in 180°C oven for 20 mins until golden brown.
